JP2010532283A - Method for making a secondary imprint on an imprinted polymer - Google Patents

Abstract

  Disclosed is a method for making an imprint on a polymer structure, comprising pressing a defined surface pattern onto the primary imprint surface of the polymer structure to form a secondary imprint on the primary imprint surface. Has been.

Description

  The present invention generally relates to a method of making a secondary imprint on an imprinted polymer.

  The ever-miniaturization of existing electronic devices has increased the need for methods and apparatus that can produce electrical components that are provided in close proximity to each other. According to empirical observations, such as Moore's Law, the number of transistors on an integrated circuit doubles approximately every two years. Nanopatterning methods are therefore very popular in the development of microelectronics and nanoelectronic devices such as integrated circuits (ICs), microelectromechanical systems (MEMS) / nanoelectromechanical systems (NEMS), optical components, and light emitting diodes (LEDs). Plays an important role. Existing nanopatterning methods include photolithography, electron beam lithography, and nanoimprint (NIL).

  Conventional photolithographic methods use light—usually ultraviolet (UV) radiation—to make a predetermined portion of a photosensitive chemical known as photoresist—which is deposited on a substrate surface—. Selectively irradiate. The selective irradiation process is typically accomplished by using a photomask to expose / block each portion of the photoresist from UV radiation. This process is usually followed by partial removal of the photoresist layer and a number of deposition processes, such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). Thus, photolithography can tightly control the shape and size of the pattern generated on the substrate, and the pattern can be generated across the substrate in a single process.

  The problem with photolithography is that the resolution of the generated pattern cannot reach below the 100 nm range. This is mainly due to the diffraction effect of light. That is, the light diffraction effect affects the accuracy in the photoresist irradiated with the light. As a result, the range of 100 nm is the limit of resolution that can be realized by conventional photolithography. Since diffraction is an intrinsic physical property of light, it can be said that the resolution limit of photolithography is quite difficult to improve. Furthermore, since the photomask used in the process is expensive and time consuming, the capital cost for photolithography increases.

  Electron beam lithography is a patterning technique that includes a procedure of scanning an electron beam in a predetermined manner over a resist-covered substrate. The purpose is to create a very small structure in the resist. The very small structure can then be transferred to other materials used in other applications such as microelectronics.

  The problem with electron beam lithography is that it is very time consuming because the patterning process is performed on a pixel-by-pixel basis. Therefore, throughput is a serious limitation, especially when writing dense patterns across a large area substrate. Furthermore, the equipment required for electron beam lithography is expensive and complicated to operate, requiring considerable maintenance effort.

  A further problem with electron beam lithography is that data related defects can occur. As can be expected, large data files (large patterns) are more susceptible to data-related defects, such as blanking or deflection errors, caused by data input mismatches to the engineering control hard wafer. Other defects, such as sample charging, backscattering, calculation errors, dust adhesion, outgassing, and contamination, can also occur. As mentioned above, the long “write time” associated with electron beam lithography tends to cause random defects, such as those listed above. These problems are particularly important when it is necessary to pattern a large surface area substrate with a large capacity throughput in a short period of time.

  NIL is another known nanopatterning technique that has the advantages of relatively low cost, high throughput, and high resolution. The mold is typically used to generate a pattern on the imprint resist using thermodynamic deformation. Subsequently, the resist is removed through an etching process, so that a pattern appears on the substrate. An imprint resist is typically a monomer or polymer composition that is cured by heat or UV light during imprinting. The bond between the resist and the mold is controlled to ensure that it is easily removed after the deformation process.

  The problem with the existing NIL is that it is necessary to produce a high resolution mold for imprinting on the resist. As the mold resolution increases, the costs associated with using the NIL method also increase. The reason for this is that mold production is a major part of the capital cost included in NIL.

  Therefore, there is a need to avoid or at least ameliorate the above problems while improving the method of imprinting high resolution patterns on the substrate surface.

  There is also a need to improve the method of imprinting high resolution patterns on the substrate surface by using the NIL method, while at the same time minimizing the cost of template production.

  According to a first aspect, onto the polymer structure, comprising pressing a defined surface pattern against the primary imprint surface of the polymer structure to form a secondary imprint on the primary imprint surface. An imprint production method is provided.

  In one embodiment, the nano-sized or micron-sized primary imprint is pressed against a nano-sized or micron-sized primary imprint surface of the polymer structure by pressing a defined surface pattern of the nano-sized or micron size. A method of making a nano- or micron-size imprint on a polymer structure is provided, comprising the step of forming a nano- or micron-size secondary imprint on the surface. In one embodiment, the secondary imprint has nano-sized dimensions, while the primary imprint has micron-sized dimensions.

  In one embodiment, at least one of the primary imprint and the secondary imprint is a longitudinal channel. Advantageously, the primary imprint channel width may be reduced to about 2 to about 13 times after the process step. In one example, the primary polymer imprint can be nanosized without using a template with a similar nanosized imprint. Therefore, by using the process disclosed herein, the channel width of the primary imprint can be significantly reduced.

According to a second aspect, a method for making an imprint on a polymer structure is provided. The method is:
(A) forming a primary imprint on the surface of the polymer structure by pressing a mold having a defined surface pattern against the surface of the polymer structure; and
(B) forming a secondary imprint on the surface of the primary imprint by pressing a mold having a defined surface pattern against the surface of the primary imprint of the polymer structure;
Have

In one embodiment, a method is provided for creating a nano-sized imprint on a polymer structure. The method is:
(A) pressing a template having a defined micron-sized channel pattern against the surface of the polymer structure to form micron-sized primary channels on the surface of the polymer structure;
(B) Pressing a template having a defined surface pattern against the surface of the micron-sized primary channel of the polymer structure to form a nano-sized secondary channel on the surface of the micron-sized primary channel The step of:
Have The width of the channel is reduced to the nanosize range.

  According to a third aspect, an imprinted polymer structure is provided. The imprinted polymer structure comprises forming a secondary imprint on the primary imprint surface by pressing a template having a defined surface pattern against the primary imprint surface of the polymer structure. Produced by the method.

  In one embodiment, a nano-sized or micron-sized imprinted polymer structure is provided. The nano-sized or micron-sized imprinted polymer structure is formed by pressing a template having a defined surface pattern against the primary imprinted surface of the nano-sized or micron-sized polymer structure. It is produced by a method having a step of forming a nano-sized or micron-sized secondary imprint on the surface.

  According to the fourth aspect, the above-mentioned imprinted polymer structure is used for nanoelectronics.

1 schematically represents a disclosed process for making primary and secondary imprints on a polymer structure. FIG. 3 illustrates a scanning electron microscope (SEM) image of a polymer structure made using the disclosed method. FIG. 6 illustrates a graph representing the trend of channel width reduction as a function of secondary template pattern. FIG. 3 illustrates a scanning electron microscope (SEM) image of a polymer structure made using the disclosed method.

  The following words used in this specification shall have the following meanings.

  The term “nanosize” refers to a structure having a thickness in the nanosize range of about 1 nm to less than about 1 μm.

  The term “micron size” refers to a structure having a thickness in the micron size range of about 1 μm to less than about 10 μm.

  As used herein, the term “channel” generally refers to a spatial region provided between a pair of protrusions extending from the bottom of the polymer structure. Here, each protrusion has a length extending along the longitudinal axis, and the height and the width are perpendicular to the longitudinal axis. As used herein, the term “channel width” refers to the width of the channel perpendicular to the longitudinal axis of the polymer structure. In general, there are multiple channels on the polymer.

  The term “photoresist” refers to a photosensitive material commonly used in semiconductor manufacturing processes. Specifically, photoresist means a material that exhibits changes in physical properties. The change in physical property is, for example, a change in solubility in a specific solvent, that is, solubilization or insolubilization due to an instantaneous change in the molecular structure of the material induced by irradiation.

  As used herein, the term “positive photoresist” refers to a polymeric material that is solubilized in a corresponding developer by exposure—typically irradiation with ultraviolet light.

  As used herein, the term “negative photoresist” refers to a polymeric material that is insolubilized in the corresponding developer by exposure—typically irradiation with ultraviolet light.

  As used herein, the term “developer” is generally used as a solvent for various types of photoresist polymers—referring to organic or aqueous media that are usually basic.

  As used herein, the term “mold” generally refers to a mold structure or master mold used to mold or manufacture a particular product.

  In this specification, the term “press” refers to compression by pressing one object against another object, pressing another object against one object, or when one object and another object approach each other simultaneously. Refers to giving power. For example, the term “press A against B” includes not only the case where object A is pressed against object B but also the case where object B is pressed against object A, and the case where object A and object B are pressed against each other.

  As used herein, the term “polymer” means a molecule having two or more units obtained from the same monomer component. As such, “polymer” includes molecules derived from various monomer components that produce copolymers, terpolymers, multicomponent polymers, graft copolymers, block copolymers, and the like.

  As used herein, the term “surface pattern” generally refers to an outer surface according to any structure disclosed herein.

  As used herein, the term “spin coating” or a grammatical change to this ending generally refers to a process in which a polymer solution is dispersed on a surface and the surface is It refers to a process in which by rotating rapidly, the solution is spread by applying centrifugal force to the solution, and a thin film of desolvated polymer is formed during the process.

  The word “substantially” does not exclude the word “completely”. For example, the mold A provided “substantially parallel” to the mold B may be completely parallel to the longitudinal axis of the mold B. Where necessary, the term “substantially” may be omitted from the definition of the present invention.

  As used herein, the term “about” used in expressing the concentration of a component of a composition is typically ± 5% of the stated value, more typically described. ± 4% of the value, more typically ± 3% of the stated value, more typically ± 2% of the stated value, even more typically ± 1% of the stated value, Even more typically it means ± 0.5% of the stated value.

  Throughout this specification, specific embodiments have been disclosed with certain numerical ranges. The description indicating the numerical range is merely for convenience and should not be construed as limiting the technical scope of the disclosed range in a state of no freedom. Accordingly, the description of a range should be understood to specifically disclose not only individual numerical values within that range but also other possible ranges within that range. For example, the description of a range from 1 to 6 is not limited to individual numerical values belonging to the range-for example 1, 2, 3, 4, 5, 6-, for example, 1-3, 1-4, 1-5, It should be understood that other ranges belonging to the ranges of 1 to 6 such as 2 to 4, 2 to 6, and 3 to 6 are also specifically disclosed. This applies regardless of the breadth of the range.

  Exemplary non-limiting examples of methods for making imprints on polymer structures are disclosed herein.

  In one embodiment, a template having a defined surface pattern is pressed onto a nano- or micron-sized primary imprint surface of a polymer structure onto the nano- or micron-sized primary imprint surface. A method of making an imprint on a polymer structure is provided, which includes forming a nano- or micron-sized secondary imprint.

  In another embodiment, the secondary imprint has a smaller dimension than the primary imprint. In one embodiment, the primary imprint may be nano-sized or micron-sized. Advantageously, the primary polymer imprint can be nanosized without using a template with a similar nanosized imprint. This effectively reduces the costs involved in nanoimprint lithography. The reason is that molds with nanosize imprints similar to the imprinted polymer are generally expensive.

  The primary imprint of the polymer structure may have a plurality of generally longitudinally extending channels imprinted on the imprinted polymer structure surface. Similarly, a secondary imprint may have a plurality of generally longitudinally extending channels imprinted on the surface of the primary polymer structure.

  In another embodiment, a method for making an imprint on a polymer structure is provided. In this method, the process step can reduce the channel width of the primary imprint.

  In one embodiment, the primary imprint channel width is selected from the group consisting of about 2 to about 13 times, about 2 to about 10 times, about 2 to about 8 times, and about 2 to about 8 times. It is possible to reduce within a range.

  Advantageously, the reduced channel width of the primary imprint can be used to deposit nanometal lines or wires.

  In one embodiment, after the primary imprint channel width has been reduced by the process step, the width can be reduced from a micron size range to a nano size range. In one embodiment, prior to the process step, the channel width of the primary imprint is from a size greater than about 2 μm, from a size greater than about 1.5 μm, from a size greater than about 1 μm, and about The size may be decreased from a size larger than 0.5 μm. In another embodiment, after the process step, the channel width of the primary imprint is less than about 800 nm, less than about 750 nm, less than about 700 nm, less than about 650 nm, less than about 500 nm. , Less than about 450 nm, less than about 400 nm, less than about 350 nm, and less than about 150 nm.

  In a special embodiment, after the process step, the channel width of the primary imprint may be reduced from a size in the range of greater than about 1 μm to a size in the range of less than about 800 nm. More preferably, after the process step, the channel width of the primary imprint may be reduced from a size in the range of greater than about 1 μm to a size in the range of less than about 500 nm.

  In one example, the polymer structure may include a photoresist. In other embodiments, the photoresist may be selected from the group consisting of SU-8, diazonaphthoquinone-novolak resin (DNA / NR), BF410 (Tokyo Ohka Kogyo), and combinations thereof.

  In one example, the polymer disclosed herein may comprise a thermoplastic polymer. Typical thermoplastic polymers include acrylonitrile butadiene styrene (ABS), acrylic, celluloid, ethylene vinyl acetate (EVA), ethylene vinyl alcohol (EVAL), fluoroplastic, liquid crystal polymer (LCP), polyacetal (POM or acetal), Polyacrylonitrile (PAN or acrylonitrile), polyamide-imide (PAI), polyallyl ether ketone (PAEK or ketone), polybutadiene (PBD), polycaprolactone (PCL), polychlorotrifluoroethylene (PCTFE), polyethylene terephthalate (PET) , Polycyclohexylenedimethylene terephthalate (PCT), polyhydroxyalkanoate (PHA), polyketone (PK), polyester, polyethylene (PE), polyetheretherketone (PEEK), polyetherimide (PEI), polyethersulfone (PES), polyethylene chlorinate (PEC), polylactic acid (PLA), polymethylpentene (PMP), polyphenylene oxide ( PPO), polyphenylene sulfide (PPS), polyphthalamide (PPA), polysulfone (PSU), polyvinylidene chloride (PVDC), spectralone, polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl acetate (PVA), Biaxially oriented polypropylene (BOPP), polystyrene (PS), polypropylene, high density polyethylene (HDPE), poly (amide), polyacryl, poly (butylene), poly (pentadiene), polyvinyl chloride Ride, polyethylene terephthalate, polybutylene terephthalate, polysulfone, polyimide, cellulose, cellulose acetate, ethylene-propylene copolymer, ethylene-butene-propylene terpolymer, polyoxazoline, polyethylene oxide, polypropylene oxide, polyvinylpyrrolidone, and mixtures thereof Polymers selected from the group are included, but are not limited to these.

  In one particular embodiment, the thermoplastic polymer may comprise polystyrene (PS).

  In one embodiment, a method for making an imprint on a polymer structure is provided. In the method, a secondary imprint may be formed on the primary imprint by performing a process step at a temperature lower than the glass transition temperature of the polymer structure. In other embodiments, the process steps include about 20 ° C to about 100 ° C, about 20 ° C to about 85 ° C, about 20 ° C to about 65 ° C, about 20 ° C to about 45 ° C, about 30 ° C to about 100 ° C. At a temperature within a range selected from the group consisting of about 45 ° C to about 100 ° C, about 65 ° C to about 100 ° C, and about 85 ° C to about 100 ° C. In one particular embodiment, the temperature conditions during the process steps are from about 40 ° C to about 65 ° C.

  In one embodiment, a method for making an imprint on a polymer structure is provided. The method further includes forming a primary imprint on the surface of the polymer structure by pressing a mold having a defined surface pattern against the surface of the polymer structure prior to the process step.

  In one example, the process steps for forming the primary imprint on the polymer structure include about 50 ° C. to about 180 ° C., about 50 ° C. to about 150 ° C., about 50 ° C. to about 100 ° C., about 50 ° C. to about It may be performed at a temperature within a range selected from the group consisting of 80 ° C, about 100 ° C to about 180 ° C, and about 150 ° C to about 180 ° C. In one particular embodiment, the temperature conditions during the process steps are from about 90 ° C to about 140 ° C.

  In one embodiment, a method for making an imprint on a polymer structure is provided. In the method, the pressure condition in the process step may be within a range selected from the group consisting of about 2 MPa to about 10 MPa, about 2 MPa to about 8 MPa, and about 2 MPa to about 5 MPa. In one particular embodiment, the pressure conditions during the process step are from about 4 MPa to about 6 MPa.

  In one embodiment, a method for making an imprint on a polymer structure is provided. In the method, the time conditions in the process steps are about 1 minute to about 15 minutes, about 1 minute to about 10 minutes, about 1 minute to about 5 minutes, about 5 minutes to about 15 minutes, and about 10 minutes. It may be within a range selected from the group consisting of about 15 minutes. In one particular embodiment, the time conditions during the process steps are from about 5 minutes to about 10 minutes.

  In one embodiment, a method for making an imprint on a polymer structure is provided. The method includes, after the process step, a third imprint on the secondary imprint surface of the polymer structure by pressing another template having a defined surface pattern against the secondary imprint surface of the polymer structure. The method further includes forming a print.

  Advantageously, the step of forming a tertiary imprint on the secondary imprint surface is performed, so that the channel width of the secondary imprint can be reduced. Accordingly, the third-order nanosize imprint can be produced without using a template having the same size as the third-order nanosize imprint.

  In one embodiment, the primary imprint and the secondary imprint may be longitudinal channels as a whole. The process step may include a step of orienting the template during the process step. Thereby, the longitudinal axis of the primary imprint and the secondary imprint is about 0 ° to about 90 °, about 0 ° to about 80 °, about 0 ° to about 65 °, about 0 ° to about 45 °, About 0 ° to about 25 °, about 10 ° to about 90 °, about 20 ° to about 90 °, about 35 ° to about 90 °, about 45 ° to about 90 °, about 60 ° to about 90 ° They are positioned at angles that are aligned with each other within a range of angles selected from the group. In one particular embodiment, the alignment angle of the longitudinal axes of the primary imprint and secondary imprint is from about 25 ° to about 60 °.

  In one embodiment, the mold may be oriented during the process step. Thereby, the longitudinal axes of the primary imprint and the secondary imprint can be substantially parallel to each other. In other embodiments, the mold may be oriented during the process step. Thereby, the longitudinal axes of the primary imprint and the secondary imprint may be aligned with each other at an angle of 45 °. In yet other embodiments, the mold may be oriented during the process step. Accordingly, the longitudinal axes of the primary imprint and the secondary imprint can be substantially perpendicular to each other.

  Advantageously, when the mold is oriented, the primary imprint and secondary imprint longitudinal axes are aligned at an angle of 0 ° to 90 ° during the process step. In addition, different types of imprinted polymer structures with different channel widths can be made. Further, when the longitudinal axes of the primary imprint and the secondary imprint are aligned substantially perpendicular to each other or at an angle of 45 °, the channel width of the primary imprint is Decrease significantly. Furthermore, the channel width decreases more greatly when the longitudinal axes of the primary imprint and secondary imprint are substantially perpendicular to each other. Thus, a primary imprint having a reduced channel width is useful for depositing nanometal lines or wires.

  The reduction in primary imprint channel width is believed to depend on a combination of several factors, such as the type of polymer used and the pressure applied during the process step. For example, different types of polymers with different thermodynamic properties are believed to affect channel width size during the process steps.

  The defined surface pattern of the mold that forms the primary imprint and / or the mold that forms the secondary imprint may have a plurality of protrusions extending from the mold. Each protrusion has a width dimension perpendicular to the longitudinal axis of the mold. In one embodiment, the width dimension of the mold that forms the primary imprint on the polymer structure is about 0.25 μm to about 10 μm, about 0.25 μm to about 4 μm, about 0.25 μm to about 2 μm, about 0.1 .mu.m. It may be within a range selected from the group consisting of 5 μm to about 10 μm, about 1.5 μm to about 10 μm, and about 4 μm to about 10 μm. In one particular embodiment, the width dimension of the primary imprint mold is from about 0.25 μm to about 2 μm.

  In one embodiment, a method for making an imprint on a polymer structure is provided. The method further includes the step of spin coating a polymer on the substrate to produce a polymer structure prior to the process step. The substrate may be chemically inert to the polymer. In one embodiment, the substrate may be selected from the group consisting of silicon, glass, metal, metal oxide, silicon dioxide, silicon nitride, indium tin oxide, ceramics, sapphire, polymer, and mixtures thereof. .

  In one embodiment, a method for making an imprint on a polymer structure is provided. The method further includes a step of removing a residual layer from the substrate after the process step. In one embodiment, oxygen plasma is introduced to remove the residual layer from the substrate.

  Advantageously, when a polymer with appropriate etch resistance is used, the underlying substrate that is etched to replicate the channel width on the substrate may be exposed by the channel width of the polymer imprint. Is possible. Thus, the imprinted polymer structure may be used as a dry or wet etch mask for etching nanometer sized sites into a substrate.

In one embodiment, a method for making an imprint on a polymer structure is provided. The method is:
(A) forming a primary imprint on the surface of the polymer structure by pressing a mold having a defined surface pattern against the surface of the polymer structure; and
(B) forming a secondary imprint on the surface of the primary imprint by pressing a mold having a defined surface pattern against the surface of the primary imprint of the polymer structure;
Have

  The accompanying drawings represent the disclosed embodiments and serve to explain the principles of the disclosed embodiments. However, it should be noted that the drawings are for illustrative purposes only and do not define limitations of the invention.

  Referring to FIG. 1, a schematic illustration of a method 10 for forming primary and secondary imprints on a polymer structure is disclosed.

  In step 1, a first silicon (Si) mold A having an imprinted surface pattern of protrusions (12A, 12B) is directly aligned on the surface of a flat polystyrene polymer substrate (PS). Yes. Here, the protrusions (12A, 12B) extend along the length of the Si mold A. The Si mold A is pressed toward the PS polymer surface at a temperature of 140 ° C. for 10 minutes at 6 MPa, so that groove gaps (14A, 14B) and protrusions (16A, 16B, 16C) is formed.

  The primary imprint is then exposed to reactive ion etching to remove the residual layer (not shown).

  In step 2, a Si mold B having a defined surface pattern composed of a plurality of protrusions (18A, 18B, 18C, 18D, 18E, 18F) is provided directly on the primary imprint surface of the PS polymer. The second Si mold B is oriented so that the longitudinal axis of the Si mold B and the longitudinal axis of the PS polymer form an alignment angle of 0 ° with respect to each other, that is, are parallel to each other.

  The Si mold B is pressed toward the surface of the primary imprint at a temperature of 65 ° C. for 10 minutes at 6 MPa, whereby a plurality of groove gaps (20A, 20B, 20C, 20D, 20E, 20F) is formed. A marked decrease in the width of the groove gap (14A, 14B) in step 1 and a significant decrease in the width of the groove gap (14A ', 14B') in step 2 can be clearly observed.

  Non-limiting examples of the present invention will now be described in considerable detail with reference to specific examples. This should not be construed as limiting the technical scope of the present invention in any way.

This example describes a template preparation and imprint method that achieves pattern size reduction with NIL by using negative photoresist (SU-8) and polystyrene (PS). Here, negative photoresist (SU-8) is sold by Microchem, USA, and polystyrene (PS) is sold by Sigma Aldrich, Singapore.
[Processing of mold]
The mold used for the primary imprint process was made of silicon (Si). The mold is cut into a size of 2 cm × 2 cm by using a diamond scriber. The cut mold was sonicated in acetone followed by isopropanol for a total of 10 minutes. The mold was further treated with oxygen plasma (80 W, 250 Torr) for 10 minutes. After oxygen treatment, the template was silanized with a 20 mM solution of perfluorodecyltrichlorosilane (FDTS) in a nitrogen glove box for 30 minutes. The relative humidity in the glove box was kept at 10-15%. The mold was subsequently washed with heptane and isopropanol. The mold was then soft baked at 95 ° C. for 1 hour in an oven to remove any residual solvent.

Prior to imprinting, all molds used were washed again for 10 minutes by ultrasonic washing with acetone and isopropanol and then dried with nitrogen before use.
[Preparation of membrane]
The full resist (SU-8) film was prepared by spin coating the resist on either a well cleaned Si wafer or indium tin oxide (ITO). The substrate was treated with oxygen plasma (80 W, 250 Torr) for 10 minutes. SU-8 2002 was originally represented by cyclopentanone and has been used as received by suppliers. The coating conditions used were formulated to give a resist film having a thickness of 2 μm. About 1 ml of resist was used for every 1 cm ^{2 of the} substrate surface. The rotation period was set to 3000 rpm in 30 seconds. After the resist is applied to the substrate, the resist-coated substrate (sample) is soft baked at 65 ° C. for 5 minutes, and then soft baked at 95 ° C. for 5 minutes. The density of the film increased. Samples were baked on a digital level hot plate.

Polystyrene (PS) films were prepared by spin coating a 12% PS solution (45k) on a well cleaned silicon wafer. The coating conditions used were formulated to give a thickness of 1.8 μm to 2 μm. About 1 ml of 12% PS was used per 1 cm ^{2 of the} substrate surface. The rotation period used was set to 500 rpm in 30 seconds to obtain a minimal residual layer on the PS sample. After spin coating, the sample was soft baked at 65 ° C. for 5 minutes to evaporate the solvent. Samples were baked on a digital level hot plate.
[Imprint conditions]
The imprinting was performed with an Obducat imprinting device. A mold was placed on top of the sample and was carried into the imprint apparatus. The resist was imprinted for 600 seconds at 90 bar and 60 bar (absolute value). On the other hand, PS was imprinted for 600 seconds at 140 bar and 40 bar (absolute value). The primary imprint was performed with a 2 μm grid template with a duty cycle of 1: 1. The secondary mold used is a 250 nm grid mold with a duty cycle of 1: 1.

  After completion of the initial process of primary imprinting and before secondary imprinting is performed, oxygen plasma (RIE made by TRION Co., Ltd.) removes the residual layer (thermodynamically deformed resist / PS region). Used to remove by etching.

  Therefore, it is important to minimize the residual layer of the primary imprint and avoid overetching of the initial primary resist structure. Further, the step of removing the residual layer allows the primary polymer protrusions to be moved laterally. Thereby, the channel width of the primary polymer can be effectively reduced during the secondary imprint process.

  An optimal etch time of 10 seconds was used to remove the residual layer by etching. A series of etching processes relating to the thickness of the remaining layer is shown in Table 1.

表１：回転条件、対応する残余層の厚さ、及び必要なエッチング時間を介したＰＳ中での残余層の最適化が示されている。

表１では、回転速度が減少するにつれてエッチング時間が増大することが示されている。

Table 1 shows the optimization of the residual layer in PS via the rotation conditions, the corresponding residual layer thickness and the required etching time.

Table 1 shows that the etching time increases as the rotational speed decreases.

  After the primary imprint and residual layer etching, a secondary imprint process is performed for resist at a low temperature of 40 ° C. (below the glass transition temperature) at 60 bar for 600 seconds and for PS at 65 bar at 40 bar for 600 seconds. It was conducted.

  For resist samples, after removal of the residual layer, the sample is exposed to UV light for 10 seconds in an imprinting apparatus, causing cross-linking within the resist structure. The sample was then baked for 2.5 hours at 180 ° C. in a convection oven. The temperature was slowly lowered so that the sample could be gradually cooled. This is to prevent thermal stress from occurring in the sample. Subsequently, the mold was removed from the sample, and the mold was separated from the substrate. The PS sample does not require any exposure or post-bake treatment and simply removes the mold to separate the mold from the substrate.

  The sample used in this example was prepared using a technique similar to that described in Example 1. The imprint method is the same as the method described in the first embodiment. This example further illustrates the use of secondary imprints to improve pattern resolution on photoresist (SU-8) coatings.

  FIG. 2A shows an SEM image of a primary resist structure after primary imprinting using a lattice-shaped template—a magnification of 5000 times. As shown, a grid pattern with a 2 [mu] m groove gap width was imprinted on a negative photoresist (SU-8) deposited on a silicon substrate. The groove gap width of 2 μm was consistent with the resolution pattern of the grid template used. The primary resist structure has a pitch of 4 μm.

  FIG. 2B shows a secondary grid pattern obtained when a 250 nm grid template (secondary template) is further imprinted on the primary imprint surface obtained from FIG. The SEM image to be shown-the magnification is 13000 times-. The longitudinal axis of the secondary mold channel was aligned to be almost parallel to the longitudinal axis of the primary imprint channel. As a result, parallel grooves are formed along the primary resist structure. In the primary imprint, it can be clearly observed that the groove gap width is reduced from 2 μm to 550 nm (a reduction of 3.6 times).

  FIG. 2 (c) shows a secondary grid pattern obtained when a 250 nm grid template (secondary template) is further imprinted on the primary imprint surface obtained from FIG. 2 (a). The SEM image to be represented-the magnification is 5000 times-is shown. The longitudinal axis of the secondary mold channel was provided perpendicular to the longitudinal axis of the primary imprint. In the primary imprint, it can be clearly observed that the groove gap width is reduced from 2 μm to 300 nm.

  FIG. 2D shows a secondary grid pattern obtained when a 250 nm grid template (secondary template) is further imprinted on the primary imprint surface obtained from FIG. The SEM image to be represented-magnification is 6000 times-is shown. The secondary mold was provided at an angle of 45 ° with the longitudinal axis of the primary imprint. In the primary imprint, it can be clearly observed that the gap of the groove width decreases from 2 μm to 281 nm.

表２：レジストポリマー層用のナノインプリントリソグラフィ（ＮＩＬ）によって作製された溝幅の減少をまとめた表

表２は、様々な位置合わせでの１次及び２次鋳型インプリントの組合せによって得られたレジストの１次構造についての溝幅の減少をまとめた表を与えている。２５０ｎｍの２次インプリント鋳型が、１次インプリントの長手軸に対して４５°又は９０°の角度をなした状態でインプリントされるときに、１次インプリントの溝幅の顕著な減少を明瞭に観測することができる。

Table 2: Table summarizing the reduction in groove width produced by nanoimprint lithography (NIL) for resist polymer layers

Table 2 provides a table summarizing the groove width reduction for the primary structure of the resist obtained by the combination of primary and secondary template imprints at various alignments. When a 250 nm secondary imprint mold is imprinted at an angle of 45 ° or 90 ° to the longitudinal axis of the primary imprint, there is a significant reduction in the groove width of the primary imprint. It can be observed clearly.

  In FIG. 3, it can be observed that the larger the imprint size of the secondary mold used, the greater the reduction in the channel width of the primary imprint.

  The sample used in this example was prepared using a technique similar to that described in Example 1. The imprint technique was similar to the technique described in Example 1. This example further illustrates the use of secondary imprints to reduce pattern resolution on the PS primary structure.

  FIG. 4 illustrates a series of SEM images of a PS structure made by the disclosed method. In this method, the effect of the pattern portion of the secondary template on the reduction of the groove width of the primary structure is studied.

  FIG. 4A illustrates an SEM image representing a lattice pattern obtained by imprinting with a 2 μm lattice-shaped primary mold—magnification is 3500 times. A groove width gap of 2 μm was observed for the primary PS structure. The groove gap width of 2 μm coincided with the resolution pattern of the lattice-shaped primary mold used.

  FIG. 4B shows a grid pattern obtained by imprinting with a 500 nm secondary mold provided at an angle of 90 ° with the primary mold following imprinting with a 2 μm primary mold. The SEM image to be represented-the magnification is 5500 times-is illustrated. In the primary imprint, it can be clearly observed that the groove width gap is reduced from 2 μm to 409 nm.

  FIG. 4 (c) shows a lattice pattern obtained by imprinting with a primary mold of 2 μm, followed by imprinting with a secondary mold of 150 nm provided at an angle of 90 ° with the primary mold. The SEM image to be represented-the magnification is 7500 times-is illustrated. In the primary imprint, it can be clearly observed that the groove width gap is reduced from 2 μm to 150 nm.

  FIG. 4 (d) shows a lattice pattern obtained by imprinting with a 2 μm secondary mold provided at an angle of 90 ° with the primary mold following imprinting with a 2 μm primary mold. The SEM image to be represented-the magnification is 2300 times-is illustrated. It can be observed that the groove width gap decreases from 2 μm to 1.7 μm.

表３：ＰＳポリマー層用のナノインプリントリソグラフィ（ＮＩＬ）によって作製されたギャップの減少をまとめた表

表３は、様々な位置合わせでの一連の１次及び２次鋳型のインプリントによって得られたＰＳの１次構造についての溝幅の減少をまとめた表を与える。ＰＳの１次構造については、９０°をなすように位置合わせされた２５０ｎｍの格子を有する２次インプリント鋳型が、１次のＰＳ構造の溝幅を減少させるのに最も有効であることが分かる。また２次鋳型の分解能が１次鋳型の分解能と同一であるときには、最小サイズの減少は非常に小さいことも分かった。

Table 3: Table summarizing the reduction in gaps produced by nanoimprint lithography (NIL) for PS polymer layers

Table 3 provides a table summarizing the groove width reduction for the primary structure of PS obtained by a series of primary and secondary mold imprints at various alignments. For the primary structure of PS, it can be seen that a secondary imprint mold with a 250 nm grating aligned to form 90 ° is most effective in reducing the groove width of the primary PS structure. . It was also found that the minimum size reduction is very small when the resolution of the secondary mold is the same as the resolution of the primary mold.

  The methods disclosed herein provide a cheaper alternative approach to obtaining nanopatterns using NIL. This is because a template having a nanometer scale pattern is not required to realize a nanometer surface pattern. That is, by pressing a mold having a surface pattern defined toward the primary imprint surface of the polymer structure, the dimensions of the primary imprint are reduced. For example, if the primary imprint is in the form of a channel, the channel width can be reduced from the micron size range to the nano size range.

  Advantageously, the channel width of the primary imprint can be reduced to a range of about 2 to about 13 times. Therefore, a nano-sized polymer imprint can be realized without using a template having an imprint of the same size as the nano-sized polymer imprint. Therefore, by using the method disclosed in this specification, the channel width of the primary imprint can be significantly reduced. Furthermore, if the longitudinal axis of the primary imprint and the longitudinal axis of the secondary imprint are substantially perpendicular to each other, or at an angle of 45 °, the channel width of the primary imprint is significantly reduced. .

  Thus, the methods disclosed herein can produce templates having high resolution patterns that can be used to deposit metal lines and thin lines that are utilized as nanoelectrodes. Advantageously, the imprinted polymer structure can be used as a dry or wet shadow mask to create nanometer sized sites in a substrate by etching.

  Various other modifications and variations of the present invention will become apparent to those skilled in the art after reading the foregoing disclosure without departing from the scope and spirit of the invention. All such modifications and variations are understood to fall within the scope of the appended claims.

Claims (25)

  Imprinting on a polymer structure having a pressing step (a) of forming a secondary imprint on the primary imprint surface by pressing the defined surface pattern onto the primary imprint surface of the polymer structure Manufacturing method.   The method of claim 1, comprising providing the secondary imprint having a smaller dimension than the primary imprint.   The method of claim 2, comprising providing the primary imprint having a nano-sized or micron-sized dimension.   The method of claim 2, comprising providing the secondary imprint having a nano-sized dimension while the primary imprint has a micron-sized dimension.   The method of claim 4, comprising providing the secondary imprint in the nanosize range.   The method of claim 1, comprising providing at least one of the primary imprint and the secondary imprint in the form of a longitudinal channel.   The method of claim 6, wherein the pressing step reduces a channel width of the primary imprint.   The method of claim 7, wherein the channel width decreases in the range of 2 to 13 times.   The method of claim 7, wherein the channel width of the primary imprint decreases from the microsize range to the nanosize range after being reduced by the pressing step.   The method of claim 9, wherein the channel width of the primary imprint decreases from a size range of less than 1 μm to a size range of less than 800 nm after the pressing step.   The method of claim 1, wherein the polymer structure comprises a photoresist.   The method of claim 1, wherein the polymer structure comprises a thermoplastic polymer.   The method of claim 12, wherein the thermoplastic polymer comprises polystyrene (PS).   The method of claim 1, wherein the pressing step (a) is performed at a temperature below the glass transition temperature of the polymer structure.   Before the pressing step (a), a pressing step (b) for forming the primary imprint on the polymer structure by pressing a mold having a surface pattern defined toward the surface of the polymer structure The method of claim 1, further comprising: At least one of the pressing steps (a) and (b)
(I) a temperature condition in the range of 40 ° C to 140 ° C;
(Ii) a pressure condition in the range of 4 MPa to 6 MPa, and (iii) a period condition in the range of 5 minutes to 10 minutes,
Executed under the conditions of at least one of
The method of claim 15. The primary and secondary imprints are in the form of longitudinal channels, and in the pressing step (a), the longitudinal axis of the primary imprint and the longitudinal axis of the secondary imprint are 0 ° to 90 ° with each other. The step of orienting the template to form an alignment angle of
The method of claim 1.   The method of claim 17, wherein the alignment angle between the longitudinal axis of the primary imprint and the longitudinal axis of the secondary imprint is 25 ° to 60 °.   The method according to claim 1, further comprising the step of forming the polymer structure by spin coating a polymer on a substrate before the pressing step (a).   The method of claim 19, wherein the substrate is chemically inert to the polymer.   21. The method of claim 20, wherein the substrate is selected from the group consisting of silicon, glass, metal, metal oxide, silicon dioxide, silicon nitride, indium tin oxide, ceramics, sapphire, polymer, and mixtures thereof. . A method of making an imprint on a polymer structure,
(A) creating a primary imprint on the polymer structure by pressing a defined surface pattern toward the surface of the polymer structure; and (b) a surface of the primary imprint of the polymer structure. Creating a secondary imprint on the surface of the primary imprint by pressing a surface pattern defined toward the
Having a method.   An imprint produced by a method comprising the step of creating a secondary imprint on the surface of the primary imprint by pressing a defined surface pattern toward the surface of the primary imprint of polymer structure Polymer structure.   By pressing a defined surface pattern toward the surface of the nano-sized or micron-sized primary imprint of polymer structure, the nano-sized or micron-sized surface is placed on the surface of the nano-sized or micron-sized primary imprint. A nano- or micron-sized imprinted polymer structure produced by a method comprising the step of producing a secondary imprint of   Use of the imprinted polymer structure according to claim 23 or 24 for nanoelectronics.

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